1. Field of the Invention
The present invention relates to dressings, in particular dressings for covering a portion of the anatomical surface of a living being, a method for preparing such dressings, and a method of treating a portion of the anatomical surface of a living being, especially a joint or a protruding part of the body.
2. Description of the Related Art
Conventionally, dressings for the treatment or prevention of wounds or pressure sores or even unbroken skin are essentially flat dressings, which are sufficiently mouldable to be applied to flat or slightly curved areas of the body. Such flat dressings are not very suitable for applying on protruding parts of the body or joints e.g. heels or especially elbows or knees having not only a very pronounced curvature but also being subject to constant bending which often causes wrinkling and focusing of stresses in the dressing often causing slipping of the adhesive and unintended detachment of the dressing.
WO 93/00056 discloses that a skin-friendly dressing having grooves or ditches surrounding a central part of the dressing has a high degree of flexibility. The ditches are surrounding a central part of the adhesive.
EP patent No. 0 768 071 discloses a wound dressing especially for use in the sacrum area, said dressing having one or more linear depressions that assist a user in applying, flexing or folding the dressing and that the dressing may have two sets of spaced parallel depressions forming a grid which is useful in the wound assessment. The thickness of the adhesive layer at the base of the depressions should at least be as great as the thickness of the border portion of the adhesive layer.
GB patent No. 1,075,939 discloses an adhesive bandage having a thermoplastic top film provided with embossments in order to allow passage of water vapour though the film.
Published EP patent application No. 0 256 893 discloses a non-adherent dressing comprising a film which contains depressions over the wound contacting area which depressions contain a viscous pharmaceutical composition which is suitable for topical application. The depressions may be in the form of a pattern of conical depressions.
GB patent No. 1,075,939 and EP patent application No. 0 256 893 are silent with respect to flexibility.
WO 99/36017 discloses a dressing comprising a substantially water-impervious layer and a skin-friendly adhesive having a pattern of indentations, which diminishes or disappears when the dressing is moisturised. The grooves are stated to have a depth of at least 25% and more preferred at least 50% of the thickness of the dressing and it is stated that the pattern may increase the flexibility of the dressing.
U.S. Pat. No. 5,356,372 discloses an occlusive pressure-reducing wound dressing consisting of an occlusive wound contacting layer and a pressure-reducing layer and it is claimed that the pressure-reducing layer has a contour for adapting to curved body surfaces. Thus, the top surface comprises a plurality of elevated domains and lowered domains providing a lower overall resistance to larger applied compressive force. However, the lowered domains between the elevated domains provide valleys extending across the pressure-reducing layer in substantially right-angled relationship to each other so that the bending of the relatively thick foam in a multiplicity of directions is facilitated.
DE 42 03 130 discloses a medical dressing, the surface of which in certain areas has been embossed so that the embossed areas are transparent. The embossed fraction of the dressing is greater than 20% of the surface for enabling a sufficient transparency to inspect the below wound and skin. DE 42 03 130 shows different embossment patterns all showing linear indentations progressing in several directions and is silent with respect to the disadvantages of such lines.
None of the above-referenced publications address the problems associated with application of dressings on protruding parts of the body such as joints e.g. heels or especially elbows or knees having not only a very pronounced curvature but also being subject to constant bending ensuring a snug fit and a safe grip and at the same time avoiding focusing of stress along lines of the indentations for avoiding formation of wrinkles or folds during application which may lead to edges not being smooth and forming points open to initiation of rolling-up or peeling of the dressing from the skin or leave a part of the edge open for attack by moisture, altogether causing a reduction of the wear time of the dressing as compared to the theoretically expected wear time of the dressing before it should be replaced.
Furthermore, it has been found that the flexibility of a dressing is important, with respect to the shape, the size and the adhesive of the dressing, not only in use but also during the application. When applying a dressing on a part of the body that is frequently bent such as the inner or outer side of a joint or inside a hand, or a protruding part of the body or a part of the body having a double curvature such as the inter digital area flexibility is a very important property as the dressing must be able to adapt to the contour of the skin surface and to follow movements without slipping the skin or exposing the skin to significant stress causing pain or unpleasant feeling and during use a sufficient flexibility enabling the dressing to follow the movement of the underlying skin is decisive for obtaining a long wear time and for reducing the risk of migration of humidity from a wound or an abrasion to neighbouring areas which may cause maceration of the skin or leakage at the edge of the dressing.
It has now been found that the wear time of dressings applied to a part of the body that is frequently bent or a part of the body having a double curvature or protruding parts of the body especially heels, knuckles, elbows or knees, the inner part of the hand or e.g. the inter digital area may be increased considerably by using a dressing of the present invention fulfilling the above-mentioned demands.